1. Field of the Invention
The present invention relates to a cooling device including a fan having a frame, and an optical device and a projector having the cooling device.
2. Description of Related Art
Conventionally, projectors that modulate a light beam irradiated by a light source in accordance with image information to form an optical image and projects the image in an enlarged manner have been used for presentations at conferences, scientific meetings, exhibitions and the like and for so-called home-theaters. Three-plate projectors have been known as such projectors. The three-plate projectors each have a light source, a color-separating optical system that separates the light beam irradiated by the light source into a plurality of color lights, a plurality of optical modulators that modulates the respective color lights separated by the color-separating optical system, a color-combining optical system that combines the light beam modulated by the respective optical modulators, and a projection lens for enlarging and projecting the light beam irradiated by the color-separating optical system.
The positions of the plurality of the optical modulators have to be precisely determined with each other so as not to cause pixel shift between the pixels of the image formation area of the respective optical modulators. Accordingly, the respective optical modulators are fixed and integrated to the color-combining optical system after adjusting the relative positions thereof to form an optical device. Further, a clear image cannot be formed unless the image formation area of the optical modulator is located at the back-focus position of the projection lens. Accordingly, an L-shape-sided assembly has been conventionally used, where the optical device is mounted on an interior side of the horizontal portion of the L-shape of the assembly and the projection lens is attached to the exterior side of the L-shape of a vertical portion vertically provided on the horizontal portion. According to the above optical device, since the optical device can be manufactured independent of the assembly of the projector, the assembly process of the projector can be simplified.
Such optical devices also include optical elements such as polarization plates in addition to the optical modulator, which are weak to heat and are required to be efficiently cooled. Accordingly, a cooling fan is disposed on the lower side of the horizontal portion of the assembly and a hole is provided on the horizontal portion, where air is blown by the cooling fan to cool the optical device (see Japanese Patent Laid-Open Publication No. 2001-100185).
However, in the above optical device, since the optical device is cooled only by the air blown by the cooling fan, the heat of the optical device that increases in accordance with intensifying illuminance of the light source cannot be efficiently cooled.